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| 54 | <H1><A NAME="SECTION004500000000000000000"> |
| 55 | 2.5 Built-in Constants</A> |
| 56 | </H1> |
| 57 | |
| 58 | <P> |
| 59 | A small number of constants live in the built-in namespace. They are: |
| 60 | |
| 61 | <P> |
| 62 | <dl><dt><b><tt id='l2h-323' xml:id='l2h-323'>False</tt></b></dt> |
| 63 | <dd> |
| 64 | The false value of the <tt class="class">bool</tt> type. |
| 65 | |
| 66 | <span class="versionnote">New in version 2.3.</span> |
| 67 | |
| 68 | </dd></dl> |
| 69 | |
| 70 | <P> |
| 71 | <dl><dt><b><tt id='l2h-324' xml:id='l2h-324'>True</tt></b></dt> |
| 72 | <dd> |
| 73 | The true value of the <tt class="class">bool</tt> type. |
| 74 | |
| 75 | <span class="versionnote">New in version 2.3.</span> |
| 76 | |
| 77 | </dd></dl> |
| 78 | |
| 79 | <P> |
| 80 | <dl><dt><b><tt id='l2h-325' xml:id='l2h-325'>None</tt></b></dt> |
| 81 | <dd> |
| 82 | The sole value of <code><tt class="module"><a href="module-types.html">types</a></tt>.NoneType</code>. <code>None</code> is |
| 83 | frequently used to represent the absence of a value, as when default |
| 84 | arguments are not passed to a function. |
| 85 | </dd></dl> |
| 86 | |
| 87 | <P> |
| 88 | <dl><dt><b><tt id='l2h-326' xml:id='l2h-326'>NotImplemented</tt></b></dt> |
| 89 | <dd> |
| 90 | Special value which can be returned by the ``rich comparison'' |
| 91 | special methods (<tt class="method">__eq__()</tt>, <tt class="method">__lt__()</tt>, and friends), |
| 92 | to indicate that the comparison is not implemented with respect to |
| 93 | the other type. |
| 94 | </dd></dl> |
| 95 | |
| 96 | <P> |
| 97 | <dl><dt><b><tt id='l2h-327' xml:id='l2h-327'>Ellipsis</tt></b></dt> |
| 98 | <dd> |
| 99 | Special value used in conjunction with extended slicing syntax. |
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